Centrifugal unloader for compressors



Nov. 7, 1950 E. NATHAN 9 CENTRIFUGAL UNLQADER FOR COMPRESSORS Filed June 29, 1 946 INVENTOR Ell/15' fVczZ/zaxz ZWMW ATTORNEY Patented Nov. 7, 1950 I 2,529,349 CENTRIFUGAL UNL'OADER FOR COMPRESSORS Ellis Nathan, Easton, .Pa., -assi gnor to Pennsylu vania Pump & Compressor Company, Easton, Pa., a corporation of Pennsylvania Application Ma, 1948, Serial No. 680,501};-

.This invention relates to compressors for air and gasses and particularly to a starting unloader for a motor driven Compressor. I

An object of the invention is to provide. an improved} centrifugally operated valve adapted to .be moved from its unloading position to its loading position when the motor and compressor reacha predetermined speed of rotation.

I' ;A feature that enables the above object to be accomplished is that the valve itself is weighted and is normally held by a spring in an unloading position while the compressor is at rest or coming up to speed, the valve being movable to its loading position against the pressure of the spring as soon as the compressor reaches a predetermined speed of, rotation. 1 v

Another object of the invention is to'provide a; compact rotating valve bodyydrivenby the.

compressor motor, the valve body being continuously connected to the receiver and to the unloading devices by suitable conduits during its,

rotation.

In motor driven compressors it is desirable to start the motor, while pressure is in the receiver, with the compressor unloaded so that an extremely heavy load will not be applied to the motor when starting. As soon as the motor has acquired normal speed the compressor can be loaded without overloading the motor. It is to provide a convenient valve mechanism for maintaining the compressor unloaded until the motor acquires normal rotative speed and then to load the compressor that the present mechanism'has been developed.

Other objects and advantages will be apparent from the specification and claims, and from the drawing which illustrates what is now considered to be a preferred embodiment of the invention.

In the drawings: Figure 1 is a side elevation of a complete motor driven compressor installation having the present invention applied thereto, and

Fig. 2 is a sectional view of the rotatable centrifugal valve forming the present invention.

In its preferred form the invention may include the following principal parts: First, a compressor cylinder; second, a receiver connected thereto; third, unloader valves preferably controlling the intake valves of the compressor; fourth, a motor drivingly connected to the compressor; fifth, a rotatable valve body having a spool valve therein normally held in one position and having a weighted end; and sixth, conduits leading to ports in the valve body opened and closed by movements of the valve, the conduits being connected '3 Claims (cacao-e9) to the compressor receiver and to the unloading devices.. I I

, Referring jdetail to figuresof the drawing, there is shown at ill-a compressor of, standard or conventional double-acting type having an intake at 12 and a discharge at l4 connected to any form of receiver l6.

opposite ends of the cylinder, the intake valves being movable to position to load or unload the compressor by suitable devices i8 whichmay be,

similar to those shown and described in the patent'to Merwarth granted December 31, 1929, No. 1,741,426.

. The compressor, as shown is operated by an pressure within the receiver It does not over-,

burden the motor 20, but with discharge pressure within thewreceiveritithe compressor II] should be, J allowed to, operate idly, without compressing any airor gasu'ntilthe motor 20 is running at approximately normal speed.

I Driven from the main crank shaft 22 of the compressor, as by means of a belt 24, is a rotating valve body 28'. shown,'the valve body 26 may be supported upon a suitable. bracket 28. Onithe valve body26 is a pulley 30 formed thereonover which the belt 24 rides. To rotatably support the valve body 26 an anti-friction bearing 32 may be employed at one end. The body 26 is also supported'by engagement of its opposite end with a connection block 34 spring pressed in one direction by a suitable spring 36. Spring 36 surrounds a nut 35 threaded to a bolt 31 supported in the bracket 28. The inner end of bolt 31 is squared and fits within a suitable recess formed in the connection block 34.

The connection block 34 is coupled to pipes 38 and 40, pipe 38 extending to the valve unloaders l8 and pipe 40 extending to the receiver l6. Pipes 38 and 48 connect in the block 34 with ports within the revolving valve body in a manner so that pipe 38 connects with the cylinder for an unloader valve 42 at ports 44 and 46 and pipe 40 at port 48. The valve 42 has a heavily weighted end and two neck portions so that three heads are formed closely fitting the cylinder as shown. The connection between pipes 38 and 48 and the ports 39 and 48 is maintained substantially pressure tight by means of the spring 36. A' spring Sllnormally holds the valve 42in Intake and discharge valves (not shown) are provided at' the position shown while the compressor is at rest and until it acquires substantially normal speed. In this position of the valve 42 when the compressor is not running or is coming up to speed pipe 40 is connected at port 48 to the valve cylinder and pressure from receiver It may pass the neck of valve 42ito port 44 a'nd through; the conduit 3'9 to pipe 38 and thence to the unloaders l8.

heavily loaded. As soon as the compressor motor 26 reaches substantially normal speedithewalve 42 moves radially outward from the axis of rota-1;

tion of the valve body 26 against, the pressure of spring 58. This moves the 'fwei'ghted 'endiof .15

the valve 42 far enough to uncover port 52 so. that the pressure acting on the unloader l8 supplied through pipe 38 may "exhaust to atmosphere. or small end of the valve 42 moves to close port' reachingthe valve cylinder'throughpipe'40. This movement of the. valve 42 also moves thefintermediate head to uncover conduit; 39- at the same timeit'closes. port 48.

As soon as pressure in conduit 38: has b'een released by. openingpipe 38 and conduit 39 to atmosphere, the unload'ers 18 are renderedinop erative and the intake valvesjof the compressor can function normally; v j 1 It will be. understood that unloaderdevices l8 mayalsobelcontrolled to unload the compressor when the maximum discharge pressure is reached in the receiver Hi. The centrifugal valve. 42, however, is employed only for maintaining the compressor unloaded during'startingofthe motor 20. I0" vary the speed at which the valve 42 will move, to its" operative or leading position, it is only necessary to vary" the I pressure exerted by .spring'50. This maybe done by adjustment of screw 54 hearing against the outer end of pr n 7 ill claim as my inventionz,v

A centrifugal starting unloader for a motor. driven compressor comprising, arotatable valve body driven by the compressor motor,. a receiver for, said ..compressor, unloading devices therefor, conduits from the compressor receiver and to said compressor .unloader devices communicateing with said valve body,.. and a valve within said. body controlling said, conduits, said valve being spring. pressed in. a direction to normally admit, discharge pressure to said compressor. unloading devices, and said valve. being movable, when said compressor is. operating. at. substantially normal, speed, to a position to exhaustpressure from said,

4 unloading devices to atmosphere and permit normal operation of the compressor.

2. A centrifugal starting unloader for a motor driven compressor comprising a rotatable valve body driven by said compressor motor, a receiver for saidcompressor, unloading devices therefor, separate conduits-connectingsaid valve body with the compressor receiver and'with said compressor The motor will therefore not be, unloading devices, a valve movable within said connect pressure within said receiver with said *fun'Ioader devices, said valve being moved when .said. compressor. is operating at normal speed to 'a' position cutting, off pressure from said receiver "rotatable body and normally held in a position to to said. unloading devices and connecting said unloading devices to atmosphere to permit nori that operation of tlie compressor.

Simultaneously, the head at the, opposite 3. A centrifugal loading valve for a motor driven compressor comprising a. rotating valve body driven by said compressor motor, a receiver for said compressor, unloading devices therefor, conduits connecting said body tosaid receiver and to said unloading devicesfor-said compressor, a; c onnectionblock for'said'conduits, and resilient -mea'ns to maintain said'connectionj block in contact with an end face of said valve body, a spool valve rotatable with and movable radially of" said valve body, said valve in one position connecting said' receiver and unloading devices, and in another position cutting off receiver pressure from said unloading devices and connecting said'unloading devices to atmosphere, a spring normally retaining said valve in position to maintain pres sure within said-funlo'ader devices, said valve be ing Weightedat one. enol whereby at a predetermined speed of said compressor said valvewill be moved against the pressure of" said spring to close the conduitl'from the receiver and exhaust receiver pressure from said unloader devices to atmosphere and permit normal operation of said, compressor.

V ELLIS NATHAN.

. REFERENCES CITED The'following' references are of record in the file. Of" this patent:

UNITED-STATES PATENTS 

